The invention pertains to a method and an apparatus for treating ballast water with acrolein, as well as a mixing device, a feed device and a reactor device for an apparatus for treating ballast water with acrolein.
It is already known that ballast water can be disinfected on ships by use of acrolein. Already by adding 5 to 15 ppm acrolein to the ballast water, bacteria, algae, zebra mussels and other organisms of the zooplankton can be killed, and, thereby, the transfer from one port to another one can be surely eliminated. The advantage of the use of acrolein is the sustain ability in particular with respect to larvae of zebra mussels, and the fact that acrolein disintegrates by itself within a few days, i.e. no new burden of the port basin by this biocide is encountered upon discharging of the ballast water in the port of destination.
These advantages are accompanied by the fact that the handling, the transportation and the storage of pure acrolein cannot be carried out on ships because acrolein is a highly poisonous liquid doing the effects of teargas, and that the personnel on board would be forced to carry out the handling of this biocide only with a complete ABC protective clothing and using gasmasks.
Aqueous solutions of acrolein are not poisonous and can be safely handled, however, such solutions can only be handled during a few days such that the use on ships is impossible because of logistic problems.
From DE-GM 20 2007 004 912, a apparatus is known in which the ballast water is pumped by means of a pressure rising pump through a water jet pump, and the low pressure zone of the water jet pump is hydraulically connected via a control valve to a reaction container which has separate inlet openings for acrolein acetal, acid and hydrolysis water applied on the outside. In the reaction container, an aqueous acrolein solution is generated which is mixed to the ballast water in the water jet pump such that the organisms in the ballast water are killed by the acrolein. In the apparatus of DE-GM 20 2007 004 912, acrolein acetal can be used directly without a previous mixing with a solution agent being necessary. The same is true for the acid used as a catalyst which acid can be dosed into the apparatus without previous dissolution with water. The hydrolysis water is taken from the water apply system on board. Although the problem with the handling, the transport and the storage of pure acrolein on ships is solved in this apparatus, there are problems of the dimensioning, in particular of the water jet pump and the reaction container, with increasing requirements of throughput.